The present invention relates to a method and an instrument for manufacturing elements including micro-miniature patterns on a substrate and particularly to an inspecting instrument and a method of inspecting micro-miniature patterns such as the circuits or the like in a semiconductor device and a liquid crystal device and more particularly to an inspecting instrument and a method of inspecting patterns on a wafer that is placed in the course of manufacture of semiconductor device and a method of manufacturing a semiconductor device using the same.
A related art will be explained using an example of inspection of a semiconductor wafer.
A semiconductor device can be manufactured by repeating the process to transfer the patterns formed mainly on a photo-mask to the semiconductor wafer with the lithography and etching steps. In the semiconductor device manufacturing process, since adequacy of lithography step, etching step and the other various steps and generation of particle will give large influence on the manufacturing yield of semiconductor device, the method of inspecting the patterns on the semiconductor wafer in the manufacturing process has been introduced in order to quickly or previously detect generation of irregularity and defect and then feed back such data to the manufacturing process.
As a method of inspecting the defect existing in the patterns formed on a semiconductor wafer, a defect inspecting instrument has been put into the practical use to irradiate a semiconductor wafer with the white light and compare the circuits patterns of the same type of a plurality of LSIs using an optical image. For example, in the inspecting method using an optical image, a method of detecting a defect has been disclosed as described in the JP-A No. H3-167456 in order to focus the light beam to the optical lighting area on the substrate with a time delay integration sensor and then compare such focused image with the previously input design information.
Moreover, JP-A No. H9-138198 discloses a method of inspecting only particle or defect by detecting the diffracted light beam or scattered light beam through radiation of laser beam and then discriminating the regular diffracted light beam from the circuit pattern and the scattered light beam from particle or defect of irregular shape.
Moreover, with introduction of micro-miniaturization of circuit pattern, complicated shape of circuit pattern and versatile materials, it has now become difficult to detect the defect of optical image. Therefore, there is proposed an inspection method through comparison of circuit patterns using an electron beam image having the higher resolution that of the optical image.
As the pattern comparison inspection instrument using electron beam, Journal of Vacuum Science & Technology B, Vol. 9, No. 6., pp. 3005-3009 (1991), Journal of Vacuum Science & Technology B, Vol. 10, No. 6, pp. 2804-2808 (1992), JP-A No. H5-258703, U.S. Pat. No. 5,502,306 and JP-A No. H10-234543 disclose a method to automatically detect a defect by irradiating a conductive substrate (X-ray mask or the like) with the electron beam having an electron beam current that is 1000 times or more (10 nA or more) the ordinary SEM, detecting any one of generated secondary electron, reflected electron and transmitting electron and then comparing the image formed from such signal for the inspection purpose. This inspecting method is called hereinafter the wafer inspection system using electron beam.
In the wafer inspection using electron beam, an image having the resolution higher than that of the wafer inspection system or the inspection using laser can be obtained. Therefore, an ultra-miniature particle or defect on a micro-miniature circuit pattern can be detected. In addition, conductivity/non-conductivity of circuit pattern, electrical defect such as wiring and short-circuit of transistor generated at the surface or lower layer can be detected from voltage contrast reflecting potential difference at the surface on the secondary electron radiation efficiency due to the influence of charging by radiation of electron beam. The voltage contrast and the technology using the same are disclosed on the pages 839 to 841 of the “ELECTRON, ION BEAM HANDBOOK” (Published by Nikkan Kogyo Shimbun Co. Ltd.).
In the wafer inspection system and inspection using the laser, particle and defect of circuit pattern shape are detected. For the particle and defect detected, it is required to observe in detail the contents thereof in order to identify the cause of generation. Therefore, a method is now employed to receive the positional information of particle or defect detected with each inspection instrument through a communication network or medium and observe such information in the high magnification factor and high resolution with an optical microscope unit image, laser microscope unit image or electron beam image. With development in micro-miniaturization of pattern and defect or particle detected, an electron beam image can be observed in detail with the higher resolution in comparison with the optical microscope unit image or laser microscope unit image. Therefore, the observation method by the electron beam image is now widely employed. The observation instrument using such electron beam image is called, hereinafter, the review SEM.
The review SEM and an observing method in this review SEM are respectively disclosed in the JP-A No. H9-184715 and No. H10-135288. In regard to the particle and pattern defect detected with the wafer inspection system and laser inspection system as explained above, detail shape observation has become possible using the review SEM that can allocate the observation area and observe this area with the electron beam image by receiving the positional information of these inspection instruments.
However, in the wafer inspection system using electron beam, an electrical defect such as short-circuit or disconnection of transistors generated in the lower layer even if there is no irregular phenomenon in the shape of surface can be detected through the voltage contrast. It has been attempted to observe the detail of such electrical defect detected with such wafer inspection system using electron beam with an ordinary SEM, wafer inspection system or review SEM but it has been accompanied with the problem that voltage contrast cannot be obtained, disabling the observation. Regarding this problem, the review SEM that enables both high resolution observation of particle and pattern shape defect and detail observation of electrical defect that can be realized with voltage contrast has not yet been proposed in the related art.
As is explained above regarding the related art, as a result of application of wafer inspection system using laser in addition to wafer inspection system and inspection system using laser to various ultra-fine circuit patterns as well as semiconductor device, it has become possible now to detect the defects such as particle and pattern figure defect and various defects such as electrical defects like the open/short-circuit of transistors and the defects such as conductivity defect of hole pattern or the like that cannot be detected only from the figure of surface.
In order to improve the circuit pattern manufacturing process based on the result of defect detection with the wafer inspection system using electron beam, it is necessary to review in detail the contents of detected defect and execute the detail classification of particle, defect in the figure and electrical defect or the like to identify the cause of generated defect from the review result and classification result.
On the occasion of reviewing irregularity and particle in the figure of surface using the review SEM, it is effective to introduce a method of reviewing the SEM image that can be obtained by irradiating the review area under the high resolution condition that is realized with the electron beam squeezed to narrow beam and then detecting the generated secondary electron beam. In the case of SEM image, since the surface roughness information is included in the reflected electron generated when the review object is irradiated with the electron beam, it is effective to introduce a method to detect and review the reflected electron including the surface roughness information on the occasion of reviewing the surface height condition of the review object. Therefore, in order to simultaneously review the figure and material information and surface roughness information, it is preferable to install a plurality of detectors to discriminate and detect the figure and material information and the surface roughness information. On the other hand, the observation conditions such as electron beam current and scan speed or the like that are suitable for review of electrical defects from the voltage contrast are different from the conditions that are suitable for review of surface figure defect and particle.
In the cited references, the review SEM for reviewing in high resolution the surface and particle figures has been described, but these also include a problem that the observation conditions that are suitable for observation of electrical defects cannot be set easily. Thereby, this review SEM has always been accompanied with the problem that the electro-optical conditions must be manually set depending on the review purpose and therefore adjustment requires a large amount of time and labor.
Moreover, in the review SEM, it is required to receive the positional information of the defect detected with various kinds of inspection instruments with communication or medium and an image of defect is formed by scanning to the defective position and therefore high accuracy positioning is necessary to review fine particle and defect. In the method and instrument of the related art, rotation has been compensated through the alignment using the patterns of two points on the wafer 2 as the review object, but such compensation has a problem in reception of positional information pieces among various instruments that a delicate deviation is generated in the magnification factor of coordinate system and in the positional information and thereby the position is displaced at the time of extracting the sight of defective position.
Moreover, in various inspection instruments, various inspections are executed for the wafers that are manufactured from time to time in the semiconductor manufacturing process. Therefore, a large amount of particles and defects can be detected. It is of course required to know the detail contents of the detected defect and particles, but in this case, a problem rises that a large amount of time is required in such a case that all defects of all wafers are reviewed with the existing review SEM. Therefore, it has been requested to select the review areas from a large amount of defects for the highly efficient detection of characteristics of defects. Moreover, it has also been required to review and classify the selected defects automatically at a higher speed.